[opwig tests] started refactoring - all variable tests updated
[opwig tests] updated and moved base MDTest class to opwig_test.cc; updated most of namespaces tests;
[opwig] updated md::Class so that NestedNamespacesNum return 0 instead of exception
[opwig tests] updated base metadata test class with 'class' functions and updated all class tests to use it;
[opwig tests] updated base metadata test class with 'function' methods, and updated all function tests to use them;
[opwig] Updated all class members unit tests and changed md::Class constructor list to vector
Merge branch 'refactortests' into dev